unit 4, genetic diversity and natural selection Flashcards
what is genetic diversity?
number of different alleles in a population
what is natural selection?
-process that leads to evolution
-can only occur if there is genetic diversity
-results in species being better adapted to their environment
what is evolution?
is the change in allele frequency over many generations in a population
what are the three adaptions?
- anatomical
-physiological
-behavioural
what is the process of natural selection?
- new alleles for a gene are created in random mutation
-if new allele increase rate of survival in that environment then they are more likely to survive and reproduce
-through reproduction the advantageous allele is passed onto next generation
-over many generations the new allele increases in frequency in population
what are the three types of selection?
-directional
-stabilizing
-disruptive
what is directional selection?
-extreme has selective advantage
-occurs when there is a change in the environment
-modal trait changes
e.g.) antibiotic resistance
what is stabilizing selection?
-modal trait is selective advantage
-no change in environment
-trait remains same
-standard deviation decreases
e.g.) human birth weight
what is disruptive selection?
-selection pressure toward two extremes
- two curves
e.g.)bird beak lengths
what is discontinuous variation?
- distinct categories
-no in-between category
-qualitative
what is an example of discontinuous variation?
-tongue rolling
-eye colour
-blood groups
-fingerprint
what graph is used for discontinuous variation?
bar graph
what is discontinuous variation controlled by?
-few genes
what is continuous variation?
-no distinct categories
-no limits on value
-quanitive
what are example of continuous variation?
-height
-weight
-foot length
-heart rate
